Question

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Write balanced equations that indicate the reaction happening inthe information

6) the reduction of Cu2+ to Cu is fairly slow, so we need to testto ensure that it is complete before recovering the copper metal. Asensitive test for the presence of any remaining Cu2+ in solutionis the formation of deep blue Cu(NH3)4^2+(aq) upon the addition ofexcess NH3 solution. Cu(NH3)4^2+, the tetramminecopper(II) ion, isanother example of a transition metal complex, like are ammonia,rather than water molecules(and there are only four of them)

NH3 is a ga, highly soluble in water, which hydrolyzes to formweakly basic solution:
NH3(aq) + H2O(l) <=> NH4^+(aq) + OH^-(aq)

The solution is usually called NH3 (aq). The reaction equilibriumlies far to the left and only a small amount of NH^+ and OH^- form.When a metal ion, M^2+(aq) is added to a small amount of ammoniasolution, a reaction with OH- causes a hydroxide precipitate toform. This is the case with Cu^2+, Zn2+, Cd2+, and a fewothers.

M^2+(aq) + 2NH3(aq) + 2H2O(l) <=> M(OH)2(s) +2NH4^+(aq)

If a large excess of NH3(aq) is added to the M(OH)2(s), thisprecipitate will rediscover as the soluble teraammine complexformed.

Cu(OH)2(s) + 4NH3(aq) <=> Cu(NH3)4^2+(aq) + 2OH-(aq)